Humic acids are known as natural substances of a supramolecular nature. Their self-assembly ability can affect the migration of heavy metals and other pollutants in nature. The formation of metal-humic complexes can decrease their mobility and bioavailability. This study focuses on metal ions diffusion and immobilization in humic hydrogels. Humic acids were purchased from International Humic Substances Society (isolated from different matrices-peat, soil, leonardite, water) and extracted from lignite mined in Czech Republic. Copper(II) ions were chosen as a model example of reactive metals for the diffusion experiments. The model of instantaneous planar source was used for experimental data obtained from monitoring the time development of copper(II) ions distribution in hydrogel. The effective diffusion coefficients of copper(II) ions showed the significant dependence on reaction ability of humic hydrogels. Lower amounts of the acidic functional groups caused an increase in the effective diffusion coefficient. In general, diffusion experiments seem to act as a valuable method for reactivity mapping studies on humic substances.

Faculty of Chemistry Brno University of Technology Purkyňova 118 464 612 00 Brno Czech Republic

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Manceau A., Matynia A. The nature of Cu bonding to natural organic matter. Geochim. Cosmochim. Acta. 2010;74:2556–2580. doi: 10.1016/j.gca.2010.01.027. DOI

Klucakova M., Pekar M. Study of structure and properties of humic and fulvic acids. IV. Study of complexation of Cu2+ ions with humic gels and final comparison. J. Polym. Mater. 2003;20:155–162.

Sierra J., Roig N., Gimenez Papiol G., Perez-Gallego E., Schuhmacher M. Prediction of the bioavailability of potentially toxic elements in freshwaters. Comparison between speciation models and passive samplers. Sci. Total Environ. 2017;605:211–218. doi: 10.1016/j.scitotenv.2017.06.136. PubMed DOI

Baek K., Yang J.-W. Humic-substance-enhanced ultrafiltration for removal of heavy metals. Sep. Sci. Technol. 2005;40:699–708. doi: 10.1081/SS-200042665. DOI

Christl I., Metzger A., Heidmann I., Kretzschmar R. Effect of humic and fulvic acid concentrations and ionic strength on copper and lead binding. Environ. Sci. Technol. 2005;39:5319–5326. doi: 10.1021/es050018f. PubMed DOI

Vialykh E.A., Salahub D.R., Achari G. Metal ion binding by humic substances as emergent functions of labile supramolecular assemblies. Environ. Chem. 2020;17:252–265. doi: 10.1071/EN19198. DOI

Piccolo A. The supramolecular structure of humic substances. Soil Sci. 2001;166:810–832. doi: 10.1097/00010694-200111000-00007. DOI

Alvarez-Puebla R.A., Valenzuela-Calahorro C., Garrido J.J. Theoretical study on fulvic acid structure, conformation and aggregation: A molecular modelling approach. Sci. Total Environ. 2006;358:243–254. doi: 10.1016/j.scitotenv.2004.11.026. PubMed DOI

Conte P., Piccolo A. Conformational arrangement of dissolved humic substances. Influence of solution composition on association of humic molecules. Environ. Sci. Technol. 1999;33:1682–1690. doi: 10.1021/es9808604. DOI

Picollo A., Nardi S., Concheri G. Micelle-like conformation of humic substances as revealed by size exclusion chromatography. Chemosphere. 1996;33:595–602. doi: 10.1016/0045-6535(96)00210-X. PubMed DOI

Tarasevich Y.I., Dolenko S.A., Trifonova M.Y., Alexeenko E.Y. Association and colloid-chemical properties of humic acids in aqueous solutions. Colloid J. 2013;75:207–213. doi: 10.1134/S1061933X13020166. DOI

Baalousha M., Motelica-Heino M., Galaup S., LeCoustumer P. Supramolecular structure of humic acids by TEM with improved sample preparation and staining. Microsc. Res. Tech. 2005;66:299–306. doi: 10.1002/jemt.20173. PubMed DOI

Fischer T. Humic supramolecular structures have polar surfaces and unipolar cores in native soil. Chemosphere. 2017;183:437–443. doi: 10.1016/j.chemosphere.2017.05.125. PubMed DOI

Simpson A.J., Kingery W.L., Hayes M.H.B., Spraul M., Humpfer E., Dvortsak P., Kerssebaum R., Godejohann M., Hofman M. Molecular structure and associations of humic substances in the terrestrial environment. Naturwissenschaften. 2002;89:84–88. doi: 10.1007/s00114-001-0293-8. PubMed DOI

Simpson A.J. Determining the molecular weight, aggregation, structures and interactions of natural organic matter using diffusion ordered spectroscopy. Magn. Reson. Chem. 2002;40:S72–S82. doi: 10.1002/mrc.1106. DOI

Jansen S.A., Malatz M., Nwbara S., Johnson E., Ghabbour E., Davies G., Varnum J.M. Structural modeling in humic acids. Mat. Sci. Eng. C. 1996;4:175–179. doi: 10.1016/S0928-4931(96)00151-8. DOI

Baigorri R., Fuentes M., Gonyaley-Gaitano G., Garcia-Mina J.M. Simultaneous presence of diverse molecular pattern in humic substances in solution. J. Phys. Chem. B. 2007;111:10577–10582. doi: 10.1021/jp0738154. PubMed DOI

Trubetskoi O.A., Trubetskaya O.E. Reversed-phase high-performance liquid chromatography of the stable electrophoretic fractions of soil humic acids. Eurasian Soil Sci. 2015;48:148–156. doi: 10.1134/S106422931502012X. DOI

Giachin G., Nepravishta R., Mandaliti W., Melino S., Margon A., Scaini D., Mazzei P., Piccolo A., Legname G., Paci M., et al. The mechanisms of humic substances selfassembly with biological molecules: The case study of the prion protein. PLoS ONE. 2017;14:e0213673 PubMed PMC

Nebbioso A., Piccolo A. Basis of a humeomics science: Chemical fractionation and molecular characteriazation of humic suprastructures. Biomacromolecules. 2011;12:1187–1199. doi: 10.1021/bm101488e. PubMed DOI

Chilom G., Baglieri A., Johnson-Edler C.A., Rice J.A. Hierarchical self-assembling properties of natural organic matter’s components. Org. Geochem. 2013;57:119–126. doi: 10.1016/j.orggeochem.2013.02.008. DOI

Klucakova M., Pekař M. Study of structure and properties of humic and fulvic acids. III. Study of complexation of Cu2+ ions with humic acid in sols. J. Polym. Mater. 2003;20:145–154.

Klucakova M., Veznikova K. The role of concentration and solvent character in the molecular organization of humic acids. Molecules. 2016;21:1410. doi: 10.3390/molecules21111410. PubMed DOI PMC

Klucakova M., Veznikova K. Micro-organization of humic acids in aqueous solutions. J. Mol. Struct. 2017;1144:33–40. doi: 10.1016/j.molstruc.2017.05.012. DOI

Klucakova M., Kalina M. Composition, particle size, charge and colloidal stability of pH-fractionated humic acids. J. Soils Sediments. 2015;15:1900–1908. doi: 10.1007/s11368-015-1142-2. DOI

Klucakova M. Size and charge evaluation of standard humic and fulvic acids as crucial factors to determine their environmental behavior and impact. Front. Chem. 2018;6:235. doi: 10.3389/fchem.2018.00235. PubMed DOI PMC

Varga B., Kiss G., Galambos I., Gelencser A., Hlavay J., Krivacsy Z. Secondary structure of humic acids. Can micelle-like conformation be proved by aqueous size exclusion chromatography? Environ. Sci. Technol. 2000;34:3303–3306. doi: 10.1021/es991286e. DOI

Jung A.V., Frochot C., Villieras F., Lartiges B.S., Parant S., Viriot M.L., Bersilion J.L. Interaction of pyrene fluoroprobe with natural and synthetic humic substances: Examining the local molecular organization from photophysical and interfacial processes. Chemosphere. 2010;80:228–234. doi: 10.1016/j.chemosphere.2010.04.035. PubMed DOI

Vashurina I.Y., Kochkina N.E., Kalinnikov Y.A. Effect of humic acid microadditives on the properties of starch hydrogels and films from them. Fibre Chem. 2004;36:338–342. doi: 10.1007/s10692-005-0005-9. DOI

Zielinska K., Town R.M., Yasadi K., Van Leeuven H.P. Partitioning of humic acids between aqueous solution and hydrogel: Concentration profiling of humic acids in hydrogel phase. Langmuir. 2014;30:2084–2092. doi: 10.1021/la4050094. PubMed DOI

Kanmaz N., Saloglu D., Hizal J. Humic acid embedded chitosan/poly (vinyl alcohol) pH-sensitive hydrogel: Synthesis, characterization, swelling kinetic and diffusion coefficient. Chem. Eng. Commun. 2018;206:1168–1180. doi: 10.1080/00986445.2018.1550396. DOI

Ma J., Luo J., Liu Z., Wei Z., Cai T., Zu X., Liu H., Crittenden J.C. Pb (II), Cu (II) and Cd (II) removal using a humic substance-based double network hydrogel in individual and multicomponent systems. J. Mater. Chem. A. 2018;6:20110–20120. doi: 10.1039/C8TA07250G. DOI

Hou M., Yang R., Zhang L., Liu G., Xu Z., Kang Y., Xue P. Injectable and natural humic acid/agarose hybrid hydrogel for localized light-driven photothermal ablation and chemotheraphy of cancer. ACS Biomater. Sci. Eng. 2018;4:4266–4277. doi: 10.1021/acsbiomaterials.8b01147. PubMed DOI

Sedlacek P., Smilek J., Klucakova M. How interactions with polyelectrolytes affect mobility of low molecular ions—Results from diffusion cells. React. Funct. Polym. 2013;73:1500–1509. doi: 10.1016/j.reactfunctpolym.2013.07.008. DOI

Sedlacek P., Smilek J., Klucakova M. How interactions with polyelectrolytes affect mobility of low molecular ions—2. Non-stationery diffusion experiments. React. Funct. Polym. 2014;75:41–50. doi: 10.1016/j.reactfunctpolym.2013.12.002. DOI

Chen R., Zhang Y., Shen L., Wang X., Chen J., Ma A., Jiang W. Lead (II) and methylene blue removal using a fully biodegradable hydrogel based on starch immobilized humic acid. Chem. Eng. J. 2015;268:348–355. doi: 10.1016/j.cej.2015.01.081. DOI

Klucakova M., Smilek J., Sedlacek P. How humic acids affect the rheological and transport properties of hydrogels. Molecules. 2019;24:1545. doi: 10.3390/molecules24081545. PubMed DOI PMC

Klucakova M. Agarose hydrogels enriched by humic acids as complexation agent. Polymers. 2020;12:687. doi: 10.3390/polym12030687. PubMed DOI PMC

Klucakova M., Kalina M., Sedlacek P. Grasset, L. Reactivity and transport mapping of Cu (II) ions in humic hydrogels. J. Soils Sediments. 2014;14:368–376. doi: 10.1007/s11368-013-0730-2. DOI

Klucakova M., Kalina M. Diffusivity of Cu (II) ions in humic gels-influence of reactive functional groups of humic acids. Colloids Surf. A. 2015;483:162–170. doi: 10.1016/j.colsurfa.2015.05.041. DOI

Iglesias A., Lopez R., Antelo J., Fiol S., Arce F. Effect of pH and ionic strength on the binding of paraquat and MCPA by soil fulvic and humic acids. Chemosphere. 2009;76:107–113. doi: 10.1016/j.chemosphere.2009.02.012. PubMed DOI

Paradelo M., Perez-Rodriguez P., Fernandez-Calvino D., Ariaz-Estevez M., Lopez-Periago J.E. Coupled transport of humic acids and copper through saturated porous media. Eur. J. Soil Sci. 2012;63:708–716. doi: 10.1111/j.1365-2389.2012.01481.x. DOI

Crank J. The Mathematics of Diffusion. Clarendon Press; Oxford, UK: 1956. pp. 9–26.

Cussler E.L. Diffusion: Mass Transfer in Fluid Systems. 2nd ed. Cambridge University Press; Cambridge, UK: 1984. pp. 35–37.

IHSS Natural Organic Matter Research. [(accessed on 21 February 2021)]. Available online: http:/www.Humic-substances.org.

Haynes W.M. Handbook of Chemistry and Physics. 93rd ed. CRC Press; Boca Raton, FL, USA: 2012. pp. 5-77–5-79.

Scally S., Davison W., Zhang H. Diffusion coefficients of metals and metal complexes in hydrogels used in diffusive gradients in thin films. Anal. Chim. Acta. 2006;558:222–229. doi: 10.1016/j.aca.2005.11.020. DOI

Yasadi K., Pinheiro J.P., Zielińska K., Town R.M., Van Leeuwen H.P. Partitioning of humic acids between aqueous solution and hydrogel. 3. Microelectrodic dynamic speciation analysis of free and bound humic metal complexes in the gel phase. Langmuir. 2015;31:1737–1745. doi: 10.1021/la504885v. PubMed DOI

Wang Y., Ding S., Gong M., Xu S., Xu W., Zhang C. Diffusion characteristics of agarose hydrogel used in diffusive gradients in thin films for measurements of cations and anions. Anal. Chim. Acta. 2016;945:47–56. doi: 10.1016/j.aca.2016.10.003. PubMed DOI

Garmo O.A., Royset O., Steinnes E., Flaten T.P. Performance study of diffusive gradients in thin films for 55 elements. Anal. Chem. 2003;75:3573–3580. doi: 10.1021/ac026374n. PubMed DOI

Tang J., Huang J., Tun T., Liu S., Hu J., Zhou G. Cu (II) and Cd (II) capture using novel thermosensitive hydrogel microspheres: Adsorption behavior study and mechanism investigation. J. Chem. Technol. Biotechnol. 2021;96:2382–2389. doi: 10.1002/jctb.6767. DOI

Zhang W., Song J., He Q., Wang H., Lyu W., Feng H., Xiong W., Guo W., Wu J., Chen L. Novel pectin based composite hydrogel derived from grapefruit peel for enhanced Cu (II) removal. J. Hazard. Mater. 2020;384:121445. doi: 10.1016/j.jhazmat.2019.121445. PubMed DOI

Ramirez Coutino V.A., Torres Bustillos L.G., Godinez Mora Tovar L.A., Guerra Sanchez R.J., Rodriguez Valadez F.J. pH effect on surfactant properties and supramolecular structure of humic substances obtained from sewage sludge composting. Rev. Int. Contam. Ambient. 2013;29:191–199.

Nuzzo A., Sanchez A., Fontaine B., Piccolo A. Conformational changes of dissolved humic and fulvic superstructures with compressive iron complexation. J. Geochem. Explor. 2013;129:1–5. doi: 10.1016/j.gexplo.2013.01.010. DOI

Peuravuori J., Zbankova P., Pihlaja K. Aspects of structural features in lignite and lignite humic acids. Fuel Process. Technol. 2006;87:829–839. doi: 10.1016/j.fuproc.2006.05.003. DOI

Agarose Hydrogels Enriched by Humic Acids as a Functional Model for the Transport of Pharmaceuticals in Nature Systems

Migration of copper(II) ions in humic systems-effect of incorporated calcium(II), magnesium(II), and iron(III) ions